HiI am currently building ESP8266 & Adafruit IO based home automation system using MQTT & by far it is working as expected.The ESP8266 is programmed using Arduino IDE.The main concern here is,how secure the whole MQTT system is?I mean what is the maximum vulnerability of the system as well as the private side network without any security implemented(SSL/TLS etc)??Also,i would like to know,what is the approprate way to secure the system?

Also,i would like to know,what is the approprate way to secure the system?

Secure the system against what? you get it very secure if you pull the network plug. I hope you see that you need to specify what your system is expected to do and what risks you're trying to mitigate.

Using TLS you get an encrypted communication, nothing less but also nothing more.

The MQTT system is just a message broker. If you operate your own server (in a home automation system almost mandatory) you don't need TLS (given that the network itself is a basic level of security).

"Pete, it's a fool (who) looks for logic in the chambers of the human heart." Ulysses Everett McGill.Do not send technical questions via personal messaging - they will be ignored.I speak for myself, not Arduino.